• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.371-379
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• 2008

The aim of this study was to evaluate the tightness of proximal tooth contact(TPTC) using a novel device at rest state on implant prostheses. Ten healthy young adults with class I normal occlusion consented to participate in the study and twenty patients were restored with a total 20 single-implant crowns in the left maxillary and mandibular second molars for 10 single-implant crowns, respectively. Test area were divided by 4 groups. UM describes the contact between the upper natural left first molar and natural second molar; LM the contact between the lower natural left first molar and natural second molar; IUM the contact between the upper natural left first molar and implant second molar and ILM the contact between the lower natural left first molar and implant second molar. The TPTC was measured at rest state in each area. The mean TPTC of the UM, LM, IUM and ILM was 1.48(${\pm}0.44$) N, 1.78(${\pm}0.40$) N, 1.14(${\pm}0.37$) N and 1.30(${\pm}0.32$) N respectively. These results indicate that the TPTC was less between natural tooth and implant prosthesis than between natural teeth.

• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.4
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• pp.244-252
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• 2019

Proper positioning of maxillary incisors is key to success of surgery combined treatment. Establishing surgery plan would be a difficult job if maxillary incisors are lost. Patient who lost all of her maxillary incisors due to accident came for orthodontic treatment. Through careful modification of maxillary archform, pre-surgical orthodontic treatment was conducted with four prosthetic space consolidation. Position of incisors was decided by help of 3D prosthetic set-up, and 1-jaw surgery was planned. After relative short treatment period of 28 months, final prosthesis was done. When alveolar bone loss happens, harmonious prosthesis of upper incisors is difficult. Utilizing mandibular set-back surgery and incisor positioning using 3D set-up could make a better environment for treatment outcome. Strategic pre-surgical orthodontic treatment can allow shorter time and less number of prosthetics.

• Applied Microscopy
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• v.29 no.2
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• pp.189-193
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• 1999

The response of ameloblast to long term (3 weeks) exposure to fluoride was examined in continuously erupting mandibular incisors of pregnancy rats as compared to control rats receiving a similar diet (Teklad L-356) but no sodium fluoride in there drinking water. Rats were started on water containing 0 ppm, 100 ppm, 200 ppm, and 300 ppm NaF at the beginning of pregnancy. To examine on the ultrastructural changes of the ameloblast, electron microscopy was used. The results indicated that rat incisors expressed two major changes in normal amelogenesis that could be attributed to chronic fluoride treatment. The fluoride produces marked alteration in the fine structure of ameloblast from teeth of young rats, such as large confluent distensions of the endoplasmic reticulum and swelling of isolated mitochondria, in particular on the morphology of the rough-surfaced endoplasmic reticulum. A graded series of alterations to these organelles were produced, and the severity of the changes would seem to be dependent on dose and time. This experimental data suggested that exposure prolonged of animal to high level of fluoride appears to induce morphological changes in the normal appositional growth and initial mineralization of enamel created during amelogenesis.

• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.602-618
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• 1996

The purpose of this study was to investigate the effect of acid treatment of fluoride applied dentin surface with various concentrations of phosphoric acid for various periods of time on dentin bonding. Dentin specimens prepared from freshly extracted bovine mandibular anterior teeth were divided into fluoridated and nonfluoridated groups. Specimens of nonfluoridated group were pretreated with 10% phosphoric acid for 15 seconds. Those of fluoridated groups were treated with 2% sodium fluoride or 2% stannous fluoride solution for 5 minutes and stored in $37^{\circ}C$ distilled water for 3 days, followed by phosphoric acid treatment. The concentrations of phosphoric acid were 10%, 32% or 50% and the treatment periods of time were 15, 30 or 60 seconds. All the specimens were bonded with All Bond$^{(R)}$ 2 and Bisfil$^{TM}$ composite resin. After bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, tensile bond strengths of each specimens were measured and the pretreated dentin and the fractured dentin surfaces were examined under the scanning electron microscope. The results were as follows : The tensile bond strengths from the fluoridated groups were significantly lower than those from the nonfluoridated group when the concentrations of phosphoric acid and the treatment periods of time were equal in all the groups (p<0.05). In general, the higher the concentration of phosphoric acid and the longer the treatment period of time for acid etching on the fluoride applied dentin surface, the higher were the bond strength values. Recovery of bond strength of the dentin bonding agent was better in the NaF applied group than in the $SnF_2$ applied one. SEM findings of NaF applied and $SnF_2$ applied dentin surfaces demonstrated reaction product-covered and partially or completely obstructed dentinal tubules. SEM findings of dentin surfaces fluoridated for 5 minutes followed by etching showed wider tubular openings and more clean dentin surfaces when dentin was etched with higher concentration of phosphoric acid for longer period of time. On the SEM observations of the fractured dentin-resin interface, the etched specimens of fluoridated group showed an adhesive failure mode when the concentration of phosphoric acid and the treatment period of time were same as in the nonfluoridated group. As the concentration of phosphoric acid and the treatment period of time increase during acid etching, the cohesive failure area increased. However, excessive acid etching caused adhesive failure.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.4
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• pp.324-330
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• 2018

In order to produce a stable denture for severe alveolar bone loss area, it is not only important that .0a suitable occlusion is established but also to consider compatibility with the surrounding muscle to form a suitable polished surfaces. Neutral zone is defined as a potential area where the neuromuscular system of the tongue, cheeks and lips is balanced can be determined through the neutral zone impression technique. And if artificial teeth are aligned within the neutral zone and the polished surface follows the anatomical form of the dynamic muscle, higher stability and retention of the denture may be obtained through coordination with the surrounding muscle tissue. This case is being reported since the concept of the neutral zone was applied to a patient with severely atrophic residual alveolar ridge and the result was clinically satisfactory in both function and aesthetics.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.4
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• pp.272-281
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• 2020

Agenesis of permanent tooth in adolescent patients can be treated either by orthodontic treatment for space closure or by maintaining the space until implant restoration can be carried out in adult. However, gradual atrophy of alveolar bone width makes it difficult to restore the prosthesis in the future or may cause unaesthetic results. Therefore, maintaining of not only the missing space but also the alveolar bone width should be considered. This case is a treatment whereby a temporary replacement of missing 2 mandibular incisors in adolescent patient was carried out using 2 temporary anchorage devices (TADs). Two TADs were placed horizontally 2 - 3 mm below the top of alveolar ridge, and fixed with artificial teeth by stainless steel wires extended. During the 2 year follow-up, neither gingival inflammation nor loss of the TADs have occurred. In the radiographic evaluation, the growth of the adjacent alveolar bone was not inhibited, and the width of the alveolar bone was maintained.

• Journal of Periodontal and Implant Science
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• v.52 no.4
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• pp.338-350
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• 2022

Purpose: Various studies have investigated 3-dimensional (3D)-printed implants using Ti6Al-4V powder; however, multi-root 3D-printed implants have not been fully investigated. The purpose of this study was to explore the stability of multirooted 3D-printed implants with lattice and solid structures. The secondary outcomes were comparisons between the 2 types of 3D-printed implants in micro-computed tomographic and histological analyses. Methods: Lattice- and solid-type 3D-printed implants for the left and right mandibular third premolars in beagle dogs were fabricated. Four implants in each group were placed immediately following tooth extraction. Implant stability measurement and periapical X-rays were performed every 2 weeks for 12 weeks. Peri-implant bone volume/tissue volume (BV/TV) and bone mineral density (BMD) were measured by micro-computed tomography. Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were measured in histomorphometric analyses. Results: All 4 lattice-type 3D-printed implants survived. Three solid-type 3D-printed implants were removed before the planned sacrifice date due to implant mobility. A slight, gradual increase in implant stability values from implant surgery to 4 weeks after surgery was observed in the lattice-type 3D-printed implants. The marginal bone change of the surviving solid-type 3D-printed implant was approximately 5 mm, whereas the value was approximately 2 mm in the lattice-type 3D-printed implants. BV/TV and BMD in the lattice type 3D-printed implants were similar to those in the surviving solid-type implant. However, BIC and BAFO were lower in the surviving solid-type 3D-printed implant than in the lattice-type 3D-printed implants. Conclusions: Within the limits of this preclinical study, 3D-printed implants of double-rooted teeth showed high primary stability. However, 3D-printed implants with interlocking structures such as lattices might provide high secondary stability and successful osseointegration.

• Journal of Dental Anesthesia and Pain Medicine
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• v.23 no.6
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• pp.317-325
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• 2023

Background: Local anesthetic injections may induce pain in children, leading to fear and anxiety during subsequent visits. Among the various approaches recommended to reduce pain, one is the use of a Buzzy Bee^TM device that operates on the concept of gate control theory and distraction. The literature regarding its effectiveness during the deposition of local anesthesia remains limited; hence, the aim of the present study was to determine the efficacy of extraoral cold and vibrating devices in reducing pain perception during the deposition of local anesthesia. Methods: A split-mouth crossover study in which 40 children aged 3-12 years requiring maxillary infiltration or inferior alveolar nerve block for extractions or pulp therapy in the maxillary or mandibular posterior teeth were included. The control intervention involved the application of topical anesthetic gel for one minute (5% lignocaine gel), followed by the administration of local anesthetic (2% lignocaine with 1:80,000 adrenaline) at a rate of 1 ml/ minute. Along with the control protocol, the test intervention involved using the Buzzy Bee^TM device for 2 minutes before and during the deposition of the local anesthetic injection. The heart rate and face, legs, arms, cry, and consolability revised (FLACC-R) scale scores were recorded by the dentist to assess the child's pain perception. Results: The mean age of the participants in Group A and Group B was 7.050 ± 3.12 years and 7.9 ± 2.65 years respectively. A reduction in the mean heart rate and FLACC-R score was observed during the deposition of local anesthetic solution in the tissues when the Buzzy Bee^TM was used in both groups at different visits in the same subjects (P < 0.05) The Buzzy Bee^TM device was effective in reducing the heart rate and FLACC-R scores when used during maxillary infiltration and inferior alveolar nerve block local anesthesia techniques (P < 0.05). Conclusion: The use of extraoral cold and vibrating devices significantly reduces pain perception during local anesthetic deposition in pediatric patients. Considering the results of this study, the device may be incorporated as an adjunct in routine dental practice while administering local anesthesia in children.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.3
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• pp.317-327
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• 2010

Among the permanent teeth, the first permanent molars play the greatest role in occlusion and function. So, early diagnosis for congenital missing, abnormal eruption and abnormal formation is very important to the first permanent molars in the course of arch development. The aim of this study is to analyse the differences between right and left first permanent molar's formation and eruption and between upper and lower one. A total of 545 children were selected am ong children who had visited our clinic, investigate eruption and calcification stage of permanent first molar, based on Gleiser and Hunt criteria for this study. 1. Gingival emergence of mandibular first molar is faster than maxillary first molar by 0.75~0.8 years, gingival emergence of maxillary first molar in girls faster than boys by 0.45 years, and that of mandibular first molar in girls faster than boys by 0.5 years. 2. There is the significant difference between right and left first molar on the eruption score and the calcification stage ; 5 year old children show the significant difference on the eruption score. 7 year old children show the significant difference on both the eruption score and calcification stage. 3. It shows the most active eruption movement of crown on the maxilla while the root is rapidly widening its furcation and completing root formation to 2/3, on the other hand, the most active crown emerging on mandible is shown when the root formation completed to 1/4 to 1/2.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.1
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• pp.120-147
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• 1994

This study was performed for the purpose of evaluating the stress distribution around threaded type implants, cylindrical type implants and teeth connected with rigid or non-rigid connector. The stress distribution around the surrounding bone was analyzed by three-dimensional photoelastic method. Twelve mandibular photoelastic epoxy resin models and a circular polariscope were used to record the isochromatic fringes. After the stress distribution around the implant and tooth was observed, the results were as follows ; 1. In threaded type implants, stress concentrated patterns were observed at the neck either vertical or 25 degree lateral force. 2. The stress concentrated patterns were observed at the tooth apical portion and neck portions of the implant and tooth when a threaded implant was connected with the tooth by either a rigid or non-rigid connector. More force was generated at the tooth neck portion by a rigid connector and more force at the implant neck portion by a non-rigid connector. 3. The stress concentrated patterns were observed at the apical portion of the implant and tooth when a cylindrical type ,implant was connected with the tooth either by a rigid or non-rigid connector. More force was generated at the tooth apical portion by a rigid connector and more force at the neck portion of the tooth and implant by a non-rigid connector. 4. The stress around the tooth was more equally distributed in a threaded type implant than in a cylindrical implant when the tooth was connected with either a rigid or non-rigid connector. 5. The stress around a threaded type implant was progressively more equally distributed in the following order : 1) when used a single implant, 2) a non-rigid connection with the implant and tooth, 3) a rigid connection with the implant and tooth, 4) a rigid connection with two implant fixtures.